The present invention relates to a radio transceiver device and in particular, a hand-held transceiver are used as a modular unit.
Both car telephones and hand-held transceivers are now used in the radio telephone networks. The major difference between them is that the car telephone has more output power and therefore requires more noise and spurious response rejection. In this application, the car telephone characteristics described apply equally to hand-held transceivers and their amplifier or booster combinations.
The object of the present invention is to provide a hand-held transceiver having characteristics which do not substantially change when connecting it to an amplifier device. The hand-held transceiver connected to an amplifier has characteristics which are essentially as good as those of car telephones. Another object of the present invention is to provide a hand-held transceiver which may be used in whole or in part, in a modular way as different combinations in connection with amplifying devices.
FIG. 1 shows a prior art device capable of multiple uses. The hand-held transceiver 100 and the amplifying device 200 are connected at the antenna connector A in FIG. 1. The hand-held transceiver is connected to an amplifier or a booster instead of an antenna. In the prior art the duplex filters D divide the transmission and reception frequencies within the amplifier into separate signal paths to be amplified. This prior art device has the disadvantage of being difficult to obtain the characteristics required for hand-held transceivers. The two separate duplex filters between the hand-held transceiver and the booster greatly add to the signal attenuation. The extensive amplifying required for the booster preamplifier requires extensive precautions to suppress spurious response which is difficult to achieve in the high-frequency element. This problem has been partially circumvented by adding the direct voltage input power in the hand-held transceiver. The increased power consumption, however, either shortens the life of the hand-held transceivers, or requires bigger batteries, thus being totally contrary to modern objectives.
The prior art devices must use expensive components for the connections (among others, the filters required by the duplex devices). One of the objectives of the present invention is to provide more economical connections.